1. Field of the Invention
The present invention relates to a sucrase gene derived from Coryneform bacteria. More particularly, the present invention relates to a DNA fragment derived from Coryneform bacteria and containing a gene coding for a protein having sucrase activity, a recombinant DNA obtained by inserting said DNA fragment into a vector capable of expression in Coryneform bacteria, a microorganism belonging to Coryneform bacteria harboring said recombinant DNA and capable of producing an L-amino acid or a nucleic acid, and a method for production of an L-amino acid or a nucleic acid by culturing said microorganism.
2. Discussion of the Background
Many studies have heretofore been reported regarding L-amino acid-producing microorganisms prepared using gene engineering technology. See Biotechnology Letters, Vol. 2, pp. 525-530 (1980); Appl. Environ. Microbiol., Vol. 144, pp. 181-190 (1979); and Preprint of Discussions and Lectures in the Agricultural and Chemical Society of Japan (1981), pp. 8, all incorporated herein by reference. These studies all concern the amplification of genes for the biosynthesis of L-amino acids, thereby increasing per cell productivity for the intended L-amino acids. The amplification does not increase the efficiency of L-amino acid production by enhancing the assimilation of saccharides, the raw materials to be fermented, by the microorganism.
There are some examples referring to the enhancement of the assimilation of saccharides by L-amino acid-producing microorganisms, using gene engineering technology. See Japanese Patent Application Laid-open Nos. 61-119185 and 2-171178 incorporated herein by reference. According to these studies, Escherichia coli was provided with the ability to assimilate sucrose by gene manipulation. In particular, a strain of Escherichia coli was provided with sucrose uptake activity, later hydrolyzing the sucrose into glucose and fructose, with the result that the strain was capable of utilizing sucrose as a carbon source, an ability which the strain did not possess inherently. No one has reported similar success with Coryneform bacteria, however, and no publication regarding the enhanced ability of Coryneform bacteria to assimilate saccharides such as sucrose, etc., using gene engineering technology has yet appeared.